Vitamin B6 is a micronutrient essential for normal function in humans and animals. In humans, an inadequate dietary intake has been observed in infants, the elderly, alcoholics, and hospitalized patients. Greater then recommended amounts of B6 are required in the following situations: presence of a B6 responsive genetic defect; use of a B6 antagonist for treatment of a specific disease (i.e., tuberculosis); discontinuation of a pharmacological dose of B6; pregnancy; and oral contraceptive use. Symptoms of inadequate B6 intake include convulsive seizures, abnormal electroencelphagram, hyperirritability, shin lesions and mental retardation as well as biochemical deficits. I-mice, an inbred strain, has high requirement for B6. The purpose of this study is to characterize the B6 dependency in these mice. I-mice would be the first animal model of a genetic B6 dependency. The specific aims of the study include: 1) deterrmination of the B6 requirement for I-mice; 2) determination of metabolic and behavioral abnormalities in I-mice corrected by B6; 3) determination of the critical developmental period in I-mice for B6, and 4) determination of the genetic inheritance of the B6 dependency in I-mice. The results of this study will not only characterize and assess the potential of I-mice as an animal model for a B6 responsive genetic disease, but will also contribute to our knowledge of the effects of inadequate B6 on behavior and development and the poorly understood role of B6 in carbohydrate and lipid metabolism.